I've read the Bible a couple times, and the Koran, Bigavad Gita, and both the Morman and Jehovah's Witness main texts each once through. To me, they all pretty much say the same things. Obviously just cover to cover reading is not going to give you a thorough introduction to any of them. They differ on their history because they are different branches of humanity and different eras. That's an extremely simplistic summary, but I always dumb things down to get my head around them.
I got as close to the Christian Catholic hierarchy as a gal with none of the right connections can get, having worked within a Diocesan finance and communications office, and on a Deaconate training program, also in a parish office and a Catholic cemetery office, and entered a cloistered convent. So i got a taste of all levels. I'd estimate that 90% of the people i've known and worked with are Christian, not necessarily Catholic.
My parents were two different Christian denominations and they called that a "mixed" marriage, and neither side of the family tree ever reconciled
. It boggles the mind, huh? Yet most people mean well, and merely repeat (or regurgitate) what they think
they were taught. Levels of spiritual maturity differ vastly.
I was baptized in the Dutch Christian Reformed denomination as an infant, was excommunicated (yup) in my college years for non-conformity, then received full immersion baptism again in my mid-20's by the Church of Christ denomination, and this baptism was accepted by the local Catholic Bishop's intercession when I joined the Catholic church. They did the best they could with me.